Homeowners in need of roofing 101 information before starting a new roofing project — you’ve come to the right place.
We’ve compiled a comprehensive glossary of roofing terms from basic technology all the way to the more technical. Understanding these terms will help you communicate more effectively with your roofing contractor and make informed decisions about your new roof.
Roofing Glossary
A
Algae Discoloration: A type of roof discoloration caused by algae. It is commonly called fungus growth.
Asphalt: A bituminous waterproofing agent applied to roofing materials during manufacturing.
ASTM: The American Society for Testing and Materials. A voluntary organization concerned with development of consensus standards, testing procedures, and specifications.
B
Back Surfacing: Fine mineral matter applied to the back side of shingles to keep them from sticking.
Base Flashing: That portion of the flashing attached to or resting on the deck to direct the flow of water.
Built-up Roof: A flat or low-slope roof consisting of multiple layers of asphalt and ply sheets.
Bundle: A package of shingles. There are typically 3, 4, or 5 bundles per square.
C
Caulk: To fill a joint with mastic or asphalt cement to prevent leaks.
Class “A”: The highest fire-resistance rating for roofing as per ASTM E108. Indicates roofing is able to withstand severe exposure to fire from sources outside the building.
Closed Cut Valley: A method of valley treatment in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed two inches from the valley centerline.
Counter Flashing: That portion of the flashing attached to a vertical surface above the plane of the roof to prevent water from migrating behind the base flashing.
Course: A row of shingles or roll roofing running the length of the roof.
Cricket: A peaked saddle construction at the back of a chimney to prevent accumulation of snow and ice and to deflect water around the chimney.
D
Deck: The surface installed over the supporting framing members to which the roofing is applied. Also known as sheathing.
Dormer: A framed window unit projecting through the sloping plane of a roof.
Downspout: A pipe for draining water from roof gutters. Also called a leader.
Drip Edge: A non-corrosive, non-staining material used along the eaves and rakes to allow water run-off to drip clear of underlying construction.
E
Eaves: The horizontal, lower edge of a sloped roof.
Eaves Flashing: Additional layer of roofing material applied at the eaves to help prevent damage from water backup.
Exposure: That portion of the roofing exposed to the weather after installation.
F
Felt: Fibrous material saturated with asphalt and used as an underlayment or sheathing paper.
Fiberglass Mat: An asphalt roofing base material manufactured from glass fibers.
Flashing: Pieces of metal or roll roofing used to prevent seepage of water into a building around any intersection or projection in a roof.
Flashing Cement: A trowelable mixture of cutback bitumen and mineral stabilizers includingite used to seal flashings and in some flashing applications.
G
Gable: The upper portion of a sidewall that comes to a triangular point at the ridge of a sloping roof.
Granules: Ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.
Gutter: The trough that channels water from the eaves to the downspouts.
H
Head Lap: Shortest distance from the butt edge of an overlapping shingle to the upper edge of a shingle in the second course below.
Hip: The inclined external angle formed by the intersection of two sloping roof planes.
Hip Shingles: Shingles used to cover the inclined external angle formed by the intersection of two sloping roof planes.
I
Ice Dam: Condition formed at the lower roof edge by the thawing and re-freezing of melted snow on the overhang. Can force water up and under shingles, causing leaks.
Interlocking Shingles: Individual shingles that mechanically fasten to each other to provide wind resistance.
L
Laminated Shingles: Shingles containing more than one layer of tabs to create extra thickness. Also called dimensional or architectural shingles.
Louver: A slanted opening for ventilation.
M
Mansard Roof: A type of roof containing two sloping planes of different pitch on each of four sides. The lower plane has a much steeper pitch than the upper.
Mineral Stabilizers:Ite,ite calcium carbonate,ite calcium carbonate calcium, calcium calcium carbonate calcium, calcium calcium, calcium calcium calcium, calcium calcium used inite compounds.
N
Nesting: A method of reroofing with new asphalt shingles over old shingles in which the top edge of the new shingle is butted against the bottom edge of the existing shingle tab.
Net Free Vent Area (NFVA): The area permitting unrestricted airflow, measured in square inches.
O
Open Valley: Method of valley construction in which shingles on both sides are trimmed along a chalk line snapped on each side of the valley, leaving the valley flashing exposed.
Overhang: That portion of the roof structure that extends beyond the exterior walls of a building.
P
Pitch: The degree of roof incline expressed as the ratio of rise in inches to the run in feet.
Ply: The number of layers of roofing — one-ply, two-ply.
Q
Quick-Setting Cement: An asphalt-based cement used to adhere tabs of strip shingles to the course below. Also used to adhere roll roofing laps applied by the concealed nail method.
R
Rafter: The supporting framing member immediately beneath the deck, sloping from the ridge to the wall plate.
Rake: The inclined edge of a sloped roof over a wall from the eave to the ridge.
Ridge: The uppermost, horizontal external angle formed by the intersection of two sloping roof planes.
Ridge Shingles: Shingles used to cover the horizontal external angle formed by the intersection of two sloping roof planes.
S
Self-Sealing Shingles: Shingles containing factory-applied strips or spots of self-sealing adhesive.
Sheathing: Exterior grade boards used as a roof deck material. Also known as decking.
Slope: The degree of roof incline expressed as the ratio of rise in inches to the run in inches.
Soffit: The finished underside of the eaves.
Square: A unit of roof measure covering 100 square feet.
Starter Strip: Asphalt roofing applied at the eaves that provides protection by filling in the spaces under the cutouts and joints of the first course of shingles.
Step Flashing: Flashing application method used where a vertical surface meets a sloping roof plane.
T
Tab: The exposed portion of strip shingles defined by cutouts.
Three-Tab Shingle: The most popular type of asphalt shingle, usually 12 inches by 36 inches with three tabs.
Top Lap: That portion of the roofing covered by the succeeding course after installation.
U
UL: Underwriters Laboratories, LLC.
Underlayment: Asphalt-saturated felt or synthetic material used beneath roofing to provide additional protection for the deck.
V
Valley: The internal angle formed by the junction of two sloping sides of a roof.
Vapor Retarder: Any material used to prevent the passage of water vapor.
Vent: Any outlet for air that protrudes through the roof deck such as a pipe or stack.
W
Woven Valley: Method of valley construction in which shingles from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied.
Have a Roofing Question?
Legend Roofs is happy to answer any roofing questions. Check out our most common questions page or contact us directly.